Phenol stabilized organo-phosphorous insecticides



United States Patent 3,097,128 PHENOL STABILIZED ORGANO-PHOSPHGROUS lNSECTlCIDEi Charles R. Sprinkle, Bound Brook, Leo F. Sekula, Paterson, Milton R. lohnson, Springfield, and Bertram I. Sparr, Summit, NJ assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Jan. 6, 1961, Ser. No. 80,996 7 Claims. (Cl. 167-22) This invention relates to stabilized insecticide compositions and to methods for preparing them.

The vinyl phosphates, such as dimethyl Z-carbomethoxy-l-methylvinyl phosphate and dimethyl 2,2-dichloroyinyl phosphate, and related phosphonates and phosphinates, constitute a general class of highly effective insecticides. For many =applications-as in baits, dusts or the like-these insecticides must be used in the form of dry formulations wherein they are impregnated upon solid materials. Such formulations have been prepared, and it has been found that these insecticides tend to be unstable when formulated in this manner. The reason for this instability has not been determined with certainty, but it is believed to involve in substantial part hydrolysis of the insecticides. It does not appear from examination of a variety of typical members of these insecticides impregnated upon a variety of solid carrier materials that the instability of the insecticides is due to the nature of the carrier material, but that the instability occurs irrespective of the carrier material.

Because of this instability, the potential utility and value of these insecticides has been seriously curtailed. Thus, it has been necessary in some cases to employ an excess of the insecticide to allow for decomposition before use, While in other cases it has even been necessary to prepare the formulation just prior to use, a procedure which is not only more costly, but which requires that the formulators employ special procedures for which they are not ordinarily equipped.

We now have discovered that stable dry formulations of these insecticides impregnated upon solid materials result when a minor amount of at least one phenol is intimately incorporated with the formulations and that the presence of the phenol does not adversely affect the insecticidal .properties of the formulations. As a result of these discoveries, we have found that the shelf life of typical dry formulations of these insecticides can be extended from a period so short as to prohibit use of those formulations unless prepared immediately before use, to periods so long as to permit carry-over of the unused formulations from one season to the next. Our discoveries thus substantially extend the useful applications of these insecticides.

The insecticides which have been found to exhibit instability in dry formulations on solid carriers, and which are stabilized according to this invention, have the formula:

wherein R represents hydrocarbon or substituted hydrocarbon, R represents hydrogen, halogen or one of the groups represented by R, and R" represents halogen, one of the groups represented by R or a functional organic group, n is 0, l or 2, and m+n=2, with the proviso that when n=2, both of the symbols R, together can represent a divalent organic group, each of R representing one valence bond of that group.

In these insecticides, it is preferred that when any of R and R represent halogen, the halogen be middle halogen-that is, bromine or chlorine.

3,097,128 Patented July 9, 1963 "ice These compounds are well known in the art, various classes thereof being described in such United States patents as U.S. 2,744,128; 2,788,358; 2,865,944; 2,867; 646; 2,891,887; 2,894,014; 2,894,018; 2,895,982; 2,898,- 341; 2,913,367 and 2,956,073, and in such British patents as No. 783,697.

As indicated in these patents, the organic groups represented by the symbols, R and R, preferably are low molecular Weight hydrocarbon or substituted hydrocarbon groups, for example, containing from one to ten carbon atoms each. They may be aliphatic, cycloaliphatic, aromatic or of mixed structure. When aliphatic, they may be either straight-chain or branched-chain in configuration. "lype-wise, the preferred organic groups include alkyl, cycloalkyl, aryl, alkaryl, and like groups. Illustrative examples include the methyl, ethyl, nand isopropyl groups, the various isomeric butyl, hexyl and like alkyl groups; the cyclopentyl, cyclohexyl and like cycloalkyl groups, the phenyl group; the na-phthyl group; the benzyl, phenethyl, p-methylbenzyl and like aralkyl groups; the isomeric tolyl groups, the isomeric xylyl groups, the ethylphenyl group, the 2,4-dimethyland 3,5- dimethylphenyl and like alkaryl groups, and the like.

Where n is 2that is, in the phosphate insecticidesthe two symbols, R, may together represent a divalent hydrocarbon group, each of the symbols representing one valence bond thereof. In such insecticides, it is preferred that the divalent group be an alkylene group of up to 10 carbon atoms, with 1 to 5-preferab=ly 2 to 3-carbon atoms in the chain thereof which bonds together the indicated oxygen atoms.

Further, the symbols, R, together may represent such a divalent hydrocarbon group. v

The substituted hydrocarbon groups represented by R and R are those of the above-mentioned hydrocarbon groups which are substituted by one or more non-hydro carbon substituents. The preferred substituents are mid- :dle halogen, the nitro group and amine groups represented by the formula:

and ether groups, RO-, wherein R, m and n have the respective meanings already set out herein.

Illustrative examples of the non-hydrocarbon groups include monohaloalkyl groups, such as the chloromethyl and bromomethyl groups, the 2-chloroethyl, l-bromopropyl, 3-chloropropyl and the like; polyhaloalkyl groups, such as the dichloromethyl, tribromomethyl, 1,2-dichlor0- ethyl, 2,2 dibromoethyl, 3,3 dichloro 2 bromo'propyl groups, and the like; nitroalkyl groups such as the 2- nitroethyl group; halo-substituted aromatic groups such as the various isomeric chloroand bromophenyl groups, the various isomeric polyhalophenyl groups, such as the 2,6-dichlorophenyl group, the 3,5-dibromophenyl group and the like; amino-substituted groups, such as the 2- aminoethyl group, the Z-dimethylandnoethyl group and the like; the aniline group; the p-dimethylaminophenyl group; the peethylaminobenzyl group and the like.

The symbol R", may also represent a functional organic group, such as a carboaliphaticoxy group, particularly a carboalkoxy or an alkoxyalkyleneoxycarbonyl group of up to ten carbon atoms; it may represent an ether group, RO-, wherein R has the meaning already set out; it may represent an acyloxyalkoxycarbonyl group wherein the acyl group is 3 or it may represent an amide group having the amino moiety set out above.

The preferred organic groups represented by the symbol R" are those having the formulae:

wherein X represents oxygen or sulfur and R has the meaning already set out herein.

Of particular interest because of their high insecticidal activity and tendency toward instability are the phosphates (n=2) of the foregoing generic formula wherein each R is lower hydrocarbonparticularly alkyl of up to seven carbon atoms, aryl of up to ten carbon atoms or aralkyl of up to 10 carbon atoms, particularly the phenyl or benzyl group; R bonded to the alpha carbon atom is hydrogen or one of the groups represented by R and (a) R bonded to the beta carbon atom is middle halogen and R" is middle halogen;

(b) R bonded to the beta carbon atom is hydrogen, middle halogen or one of the preferred groups represented by R, and R is a group of the formula H a. (alky1-O i 0-= hal hi1 (I) wherein alkyl represents an alkyl group of from 1- to 4 carbon atoms and hal represents middle halogen-Le, bromine or chlorine;

preferred groups represented wherein alkyl represents alkyl of from 1 to 4 carbon atoms.

Typical species of these insecticides include:

Dimethyl 2-carbomethoxy-l-methylvinyl phosphate Dimethyl 2,2-dichlorovinyl phosphate Dimethyl 2-benz-yloxyoarbonyl-l-methylvinyl phosphate Dimethyl Z-phenyloxycarbonyl-l-methylvinyl phosphate Dimethyl 2 (alpha-methylbenzyloxycarbonyl)-l-methylvinyl phosphate" Z-carbomethoxy-l-methylvinyl methyl p-nitrophenyl phosphate 2 (2 acetoxyethoxycarbonyl) l-methylvinyl dimethyl phosphate 2 (2 benzoyloxyethoxycarbonyl)-l-methylvinyl dimethyl phosphate 2 (2-methoxyethoxycarbonyl)-1-methylvinyl dimethyl phosphate Z-canbethoxy-l-methylvinyl ethyl 2-methoxyethyl phosphate Methyl Z-carbethoxy-l-methylyinyl phenylphosphonate Ethyl 2-methoxycarbonyl-1-methylvinyl dimethylaminophenylphosphonate 2 (2 carbethoxyvinyloxy) 4 methyl 2 oxy 1,3,2-

dioxaphospholane 2 (m nitrobenzyloxycarbonyl) -1-methylvinyl dimethyl phosphate 2 (p nitrobenzyloxycarbonyl) 1 l-methylvinyl dimethyl phosphate Dimethyl 1-methyl-2- (p-tolyloxycarbonyl)vinyl phosphate Dimethyl Z-phenethyloxycarbonyl-l-me-thylvinyl phosphate 2-(p methoxybenzyloxycarbonyl)-1-methylvinyl dimethyl phosphate 2-phenoxyethoxycarbonyl-l-methylvinyl dimethyl phosphate 2 (p chlorophenoxycarbonyl) l-methylvinyl dimethyl phosphate 2 (p chlorobenzyloxycarbonyl) 1 methylvinyl dimethyl phosphate Diethyl Z-carboethoxy-l-rnethylvinyl phosphate Dimethyl 2-carbomethoxy-Z-phenylvinyl phosphate Diethyl Z-carboethoxy-l-cyclopenten-l-yl phosphate Diethyl 2-carbethoxy-2-chlorovinyl phosphate Diethyl 1-ethoxy-2-carbethoxy-2-chlorovinyl phosphate 2-chloro-2-oarbethoxy-l-methylvinyl dimethyl phosphate 2-benzyloxycarbonyl-l-methylvinyl methyl phenyl phosphate Z-carbethoxyvinyl dimethyl phosphate 2-chlorovinyl dimethyl phosphate 0,0-diethyl 0-2-(ethylthio)-carbonyl-l-methylvinyl phosphorothioate O-(p-chlorophenylsulfoxylethyl) O-ethyl O-l-methyl-Z- carbethoxyyinyl phosphate 2 chloro 2 (methoxycarbonyl)-1-methylvinyl dimethyl phosphate Diethyl Z-carbethoxy-l-cyclopentenyl-yl thionophosphate 2-chloro-2-acetyl-1-methylvinyl diethyl phosphate 2,2-dichlorovinyl di-sec-b-utyl phosphate 2,2-dichlorovinyl ethyl phenylphosphonate 2,2-dibromovinyl dimethyl phosphate 2,2-dichloro-l-phenylvinyl dimethyl phosphate 2-chloro-1-phenylvinyl diethyl phosphate 2-chloro-2-carbethoxy-l-methylvinyl diethyl phosphate 2,2-dichlorovinyl ethyl 1,2-dichloropropyl phosphate Formulations of these and similar insecticides on solid carrier materials are stabilized by phenols, generally. Thus, phenol itself is a suitable stabilizer, as are other mononucle'ar phenols such as alkyl-substituted phenols. The stabilizer suitably may be a polynuclear phenol, such as alph and beta-naphthols. Polyphenols, such as hydroquinone and 2,2-bis(p-hydroxyphenyl)propane, also are suitable. Those phenols which are known to be antioxidants are suitable. These include the so-called kryptophenols--phenols substituted at one or both of the carbon atoms of the aromatic ring in position ortho to the carbon atom thereof to which is bonded the phenolic hydroxyl group-in which a stereo-chemical efiect shields or protects the phenolic hydroxyl group. These also include the polyphenols with ortho and para hydroxyl groupswhich can undergo hydroquinone-quinone transformation. It must be noted, however, that the property of being an antioxidant is not essential to the utility of a phenol as a stabilizer in the present invention, since phenol itself, and beta-naphthol, which are not considered to be antioxidants, are quite suitable as stabilizers in the present invention. Other specific phenols which may be used to stabilize these insecticides include catechol, pyrogallol, resorcinol, phloroglucinol, sesamol, B-phenylisocoumarone, the tocopherols, p-aminophenol, phenol ethers, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-alpha-dimethylamino-p-cresols, the cresols, 4,4-bis(2,6-di-tertbutylphenol), 4,4 methylene bis(6-tent butyl-o-cresol), 2,6-di-tert-butyl-alpha-methoxy-p-creso1, 2,6-di-tert-butylp-cresol, 2,2-methylenebis( t-methyl-6-tert-butylphenol), butylated hydroxyanisoles, propyl gallate, butyl ated hydroxytoluenes, 2-hydroxy-4-methoxybenzophenone, 3,5-ditert-butyl-4-hydroxybenzyl alcohol, p-octylphenol, p-nonylphenol, p-tert butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-diisopropylphenol, 2,6-di-tert-amylphenol, 2,4,6-trimethylphenol, 2,4,6-t1i-tert-butylphenol, 2,3,4,5- tetramethylphenol, pentamethylphenol and the like.

As has already been pointed out, the available evidence shows that the instability of these insecticides occurs without regard to the chemical nature of the solid carrier material usedthe instability exists with all solid carrier materials. The investigation has included such common carrier materials as various clays, including attapulgite clays, such as those sold commercially under the trade names of Attaclay and Diluex; montmorillonite clays, such as those sold commercially under the trade names Pikes Peak clay 9T66 and FF absorptive clay; dusting sulfur; cornstarch; calcium carbonate; crushed corn cobs; perlite; silicas, such as those sold under the trade names Silikil and Hi-Sil 233; kaolin clays, such as those sold under the trade names Barden AG, ASP-105 and ASP- 200; pyrophyllite, such as that sold under the name Pyrex ABB; talc, such as is sold under the trade name Emtal 23A; sand; crushed granite; sugar and diatomaceous earths, such as those sold commercially under the trade name Diacron.

The invention thus is applicable to the stabilization of solid formulations of the herein defined insecticides, im-

pregnated upon such carrier materials as kaolin clays,

attapulgite clays, diatomaceous earths, vermiculites, synthetic calcium silicates, crushed rock, rock flour, sand,

talc, powdered calcium carbonate, lime, gypsum, pyrophyllite, powdered carbn-i.e., charcoal-and the like, upon sugar or like solid materials which are useful as baits, upon organic fibrous materials, such as crushed corncobs, bagass'e, crushed or powdered nut shells, or the like.

Because of their characteristics, the preferred carrier materials for use with those insecticides defined in Formula I, column 3, are the montm-orillonite clays, particularlythat known as Pikes Peak clay. Sand, sugar, pyrophyllites, particularly that known as Pyrax ABB and talc, particularly that known as Emtal 23A, are preferred carriers foruse with those insecticides defined in Formula II, column 3. 7

But a minor amount of the phenol stabilizer is required. Thus, in most cases, from. about 0.1 to about 10 'percent by weight of stabilizer, based upon the weight of the insecticide carrier formulation, will be suflicient. This is not to say, however, that in some cases, moreor less of the stabilizer may be used to. advantage. In the great majority of cases, it will be found that at least 0.01 percent of the stabilizer will .be. required, and that seldom will an amount of stabilizer in excess of 20 percent by weight of the insecticide-carrier formulation be of such additional advantage as to be desirable.

The phenol stabilizer is incorporated in the formulation in any manner, which will enable it to be intimately contactedwith the insecticide therein. The phenol may be dissolved in the insecticide, or vice versa, depending upon the relative concentrations and solubilities of the two materials. Alternatively, and where the physical state of the phenol permits, itmay be merely intimately mixed in the already formed mixture of carrier and insecticide. Otherwise, the phenol, or the phenol and insecticide together, can be dissolved in a suitable solvent, and the solution mixed with the carrier or the carrier-insecticide mixture, as the case may be. The solvent then may be removed wholly, or in part; or in some cases, it may be desirable to include the solvent in the formulation.

" The formulations are otherwise compounded by techniques well known and generally practiced by the art. Thus, the formulation may be in'the form of a dust, in the form of granules, in the form of wettable powders, or in other forms suitable to the intended use. The formulation can contain other materials to provide necessary physical characteristics-thus, stickers, emulsifiers, spreading or wetting agents, fertilizers, other insecticides, other biocides (for example, fungicides or the like) can be incorporated in the formulation by known means. Suitably, any of the materials known to the prior art can be used, as desirable to impart the desired characteristic(s) to the final formulation. As sticking agents, there may be used casein, gelatine, cellulose derivatives such as carboxymethylcellulose, sulfite waste liquor, a guru, a water-dis- I called concentrates which contain typically from about persible synthetic resin, mineral oil, or equivalent adhesives all of which are well known in the art. Wetting agents and dispersing agents which may be employed include the various naturally occurring or synthetic surfaceacting materials known for the purpose, such as, inter alia, soaps, saponins, lecithins, fatty acid salts, long-chain alcohols, sulfonated aliphatic and/ or aromatic hydrocarbon derivatives, hydroxy esters, such as sorbitan monolaurate, pine oil, and the like. There may be employed other insecticidal agents of natural or synthetic, of mineral or organic origin, among which come into consideration sulfur, copper arsenate, pyrethrum, allethrin, DMC, HETP, malathion, DDT, BHC, lindane, and others well known to those skilled in the art. Suitable fertilizers would include ammonium sulfate, urea, ammonium phosphate, potassium nitrate, and the like. The concentration of the insecticide in the final formulation can vary widely, depending upon the use to which the formulation is to be placed. Thus, the insecticide concentration can be as little as 0.1 percent of the weight of the formulation or it can be as great as 50% or even more, in the case of the so-called concentrated formulations which are to be diluted before use. Typically, a granular formulation may contain from about 2% to about 35% insecticide by weight. This type of formulation is generally'used as such without further dilution with an insecticidally inert carrier.

Typically, a dust formulation can contain about 0.25% insecticide up to about 75% insecticide by weight. Frequently, the dust formulations are first prepared as so- 10% to about 50% insecticide dispersed in the dust, and such concentrate is further diluted to a so-called field strength dust typically having an insecticide concentration of about 0.25 to about 5'%, varying with the use desired and the potency of the toxicant.

The wettable powders typically contain a concentration of toxicant on the order of that contained in dust contrates as above described. However, they are diluted to field strength by dispersing in water rather than by dispersing in dust.

The following data exemplify practice of this invention and illustrates the benefits to be derived therefrom: In these formulations, the insecticide was dimethyl 2,2-dichlorovinyl phosphate. It was first formulated with powdered sugar as a bait for houseflies. The insecticide concentration was 1 percent by weight of the formulation. In one formulation, no stabilizer was added. In two other formulations, 2 percent by weight of the formulation of a phenol was present as stabilizer. The amount of the insecticide remaining was determined by analysis after the formulations were held at 130 F., for 2 weeks. The following data were obtained:

Percent of the insecticide decomposed No stabilizer 2,6-di-tert-butyl-4-methylphenol added as stabilizer l0 Beta-naphthol added as stabilizer 5 Percent of the insecticide decomposed No stabilizer 60 2,6-di-tert-butyl-4-methylphenol added as stabilizer 7 Beta-naphthol added as stabilizer 4 Pikes Peak Further data similarly obtained on other formulations is summarized in the following table:

Toxicant Percent dosage decomposi- (percent tion after by weight 2 weeks at of formula- 130 F.

tion) Carrier Stabilizer (percent by weight of formulation) None 2,6-di-tert-butyl 4-methyl phenol (2%). Pyrax ABB None Do Alpha-naphthol (5% N one 2,6-di-tert-bntyl 4-methyl phenol (5 Alpha-naphthol (5%) Beta-naphthol (5%) Phenol (5%) U! cum CnUrOr cncrgogo pp Percent decomposition after 2 weeks at; 130 F.

Carrier Stabilizer (percent by Weight of formulation) None 25 Hydroquinone added as 25 stabilizer (5%). 2,2 Bis(p-hydroxy-phenyl)- 25 propane (5%).

It-is evident from a review of the above data that a small quantity of the present phenol stabilizers unexpectedly provides superior protection against deterioration of the insect toxican-t when in contact with the indicated carrier materials. So, too, when others of the previously described carriers are used in the insecticide formulations comparable results are obtained.

We claim as ourinvention: l. A stable solid insecticidal composition comprising in combination:

(a) a substantially toxicologically inert solid carrier material, (b) an insecticide of the formula:

8 the amount of said phenol being sufiicient to stabilize said insecticide against decomposition. 2. A stable solid insecticidal composition comprising in combination:

(a) a substantially toxicologically inert solid carrier material,

(b) an insecticide of the formula:

0 hal (alky1-O -0( 3=( ]ha1 wherein alkyl is lower alkyl and hal is a member of the group consisting of chlorine and bromine, (c) a phenol,

the amount of said phenol being suflicient to stabilize said insecticide against decomposition. 3. A stable solid insecticidal composition comprising in combination:

(a) a substantially toxicologically inert solid carrier material, (b) an insecticide of the formula:

(H) alkyl H a1ky1-o P-0b=b- Oalky1 wherein alkyl is lower alkyl, (c) a phenol,

the amount of said phenol being sufiicient to Sta bilize said insecticide against decomposition. 4. A stable solid insecticidal composition comprising in combination:

(a) a substantially tox-icologically inert solid carrier material, (b) dimethyl 2,2-dichlorovinyl phosphate, (0) a phenol,

the amount of said phenol being sufficient to stabilize said phosphate against decomp-ositoin. 5. A composition according to claim 4 wherein the phenol is phenol.

6. A stable solid insecticidal composition comprising in combination:

(a) a substantially toxicologically inert solid carrier material, (b) dimethyl phate, (c) a phenol,

the amount of said phenol being suflicient to stabilize said phosphate against decomposition. 7. A composition according to claim 6 wherein the phenol is phenol.

2-carbomethoxy-l-methylvinyl phos- References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES King: U.S. Dept. Agr. Handbook No. 69 (1954), pp. 257-260. 

1. A STABLE SOLID INSECTICIDAL COMPOSITION COMPRISING IN COMBINATION: (A) A SUBSTANTIALLY TOXICOLOGICALLY INERT SOLID CARRIER MATERIAL, (B) AN INSECTICIDE OF THE FORMULA: 